Light emitting diode package structure

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light emitting diode package structure and, more particularly, to a package structure capable of enhancing the lighting efficiency of a light emitting diode and packaging a light emitting diode in a relatively simple process, thereby increasing the production yield and decreasing the production cost.

2. Description of the Related Art

For commercial and industrial applications, light emitting diodes provide a light source at a higher efficiency and a lower cost than incandescent lamps and fluorescent lamps. In recent years, a variety of package structures and methods have been developed for the light emitting diodes, such as a surface mounting type package structure and a flip-chip type package structure.

FIG. 1 is a cross-sectional view showing an example of a conventional light emitting diode package structure. Referring to FIG. 1, a light emitting diode <b>10</b> is mounted on a package base <b>20</b> in a flip-chip way. The light emitting diode <b>10</b> has a substrate <b>11</b>, a first conductivity semiconductor layer <b>12</b> formed over the substrate <b>11</b> and a second conductivity semiconductor layer <b>13</b> formed over the first conductivity semiconductor layer <b>12</b>. In addition, a first electrode <b>14</b> is formed over a predetermined region of the first conductivity semiconductor layer <b>12</b> while a second electrode <b>15</b> is formed over a predetermined region of the second conductivity semiconductor layer <b>13</b>. Since the manufacturing method and operation of the light emitting diode <b>10</b> are well known, they are omitted hereinafter for the sake of simplicity.

In the conventional package structure of FIG. 1, two metal solder balls <b>16</b> and <b>17</b> are formed over the first and second electrodes <b>14</b> and <b>15</b>, respectively. Subsequently, two metal solder balls <b>16</b> and <b>17</b> are, respectively, aligned with and then bonded to a first pad <b>21</b> and a second pad <b>22</b> formed over the package base <b>20</b>. Finally, a transparent resin <b>18</b> seals the light emitting diode <b>10</b> so as to complete the packaging of the conventional light emitting diode. When a power supply is applied to the light emitting diode <b>10</b> through the first and second pads <b>21</b> and <b>22</b>, the light emitting diode <b>10</b> radiates light to external space through the substrate <b>11</b> and transparent resin <b>18</b>, as indicated by an arrow of FIG. <b>1</b>.

The conventional package structure of FIG. 1 has the following drawbacks. First, the metal solder balls <b>16</b> and <b>17</b> are likely to contact with each other, resulting in a short circuit between the first and second electrodes <b>14</b> and <b>15</b>. Moreover, during the mounting of the light emitting diode <b>10</b> over the package base <b>20</b> in the flip-chip way, it is necessary for the metal solder balls <b>16</b> and <b>17</b> to precisely align with the first and second pads <b>21</b> and <b>22</b>, resulting in a more difficult manufacture and a higher production cost.

In addition, it is desired to provide a package structure having a higher efficiency of the light emitting diode than that performed by the conventional package structure of FIG. <b>1</b>. Thereby, the heat generated during operations may be reduced and then the lifespan and reliability of the light emitting diode may be enhanced.

SUMMARY OF THE INVENTION

In view of the above-mentioned problems, an object of the present invention is to provide a light emitting diode package structure capable of packaging a light emitting diode in a relatively simple process, thereby increasing the production yield and decreasing the production cost.

Another object of the present invention is to provide a light emitting diode package structure capable of achieving a higher efficiency of a light emitting diode, thereby reducing the heat generated during operations and then enhancing the lifespan and reliability of a light emitting diode.

According to one aspect of the present invention, a light emitting diode package structure includes a transparent insulating carrier base formed with a recess. A bottom surface of the recess supports a substrate of a light emitting diode. A depth of the recess is large enough for completely accommodating the light emitting diode. At least a planar metal layer is formed in a region other than the recess on a top surface of the transparent insulating carrier base. At least a wiring connects one of the at least a planar metal layer and one of two electrodes of the light emitting diode. A resin fills the recess and partially covers the at least a planar metal layer in order to seal the light emitting diode and the at least a wiring.

According to another aspect of the present invention, a recess may have at least a stepwise portion for providing at least an intermediate mesa plane. At least a planar metal layer is formed on the at least an intermediate mesa plane and connected to at least a metal pad arranged outside the recess. At least a wiring connects one of the at least a planar metal layer and one of two electrodes. A resin fills the recess in order to seal the light emitting diode and the at least a wiring.

According to still another aspect of the present invention, a light emitting diode package structure includes an insulating carrier base formed with a through hole. A substrate of a light emitting diode faces a lower opening of the through hole. A depth of the through hole is large enough for completely accommodating the light emitting diode. At least a planar metal layer is formed in a region other than the through hole on a top surface of the insulating carrier base. At least a wiring connects one of the at least a planar metal layer and one of two electrodes of the light emitting diode. A resin fills the through hole and partially covers the at least a planar metal layer in order to seal the light emitting diode and the at least a wiring.

According to still another aspect of the present invention, a through hole may have at least a stepwise portion for providing an intermediate mesa plane. At least a planar metal layer is formed on the at least an intermediate mesa plane and connected to at least a metal pad arranged outside the through hole. At least a wiring connects one of the at least a planar metal layer and one of two electrodes of the light emitting diode. A resin fills the through hole in order to seal the light emitting diode and the at least a wiring.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other objects, features, and advantages of the present invention will become apparent with reference to the following descriptions and accompanying drawings, wherein:

FIG. 1 is a cross-sectional view showing an example of a conventional light emitting diode package structure;

FIG. <b>2</b>(<i>a</i>) is a top plan view showing a transparent insulating carrier base according to a first embodiment of the present invention;

FIG. <b>2</b>(<i>b</i>) is a cross-sectional view showing a light emitting diode package structure taken along a line A-A′ of FIG. <b>2</b>(<i>a</i>) according to a first embodiment of the present invention;

FIG. <b>3</b>(<i>a</i>) is a top plan view showing a transparent insulating carrier base according to a second embodiment of the present invention;

FIG. <b>3</b>(<i>b</i>) is a cross-sectional view showing a light emitting diode package structure taken along a line B-B′ of FIG. <b>3</b>(<i>a</i>) according to a second embodiment of the present invention;

FIG. 4 is a cross-sectional view showing a light emitting diode package structure according to a third embodiment of the present invention;

FIG. 5 is a cross-sectional view showing a light emitting diode package structure according to a fourth embodiment of the present invention;

FIG. 6 is a cross-sectional view showing a light emitting diode package structure according to a fifth embodiment of the present invention; and

FIG. 7 is a cross-sectional view showing a light emitting diode package structure according to a sixth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments according to the present invention will be described in detail with reference to the drawings.

FIG. <b>2</b>(<i>a</i>) is a top plan view showing a transparent insulating carrier base <b>30</b> according to a first embodiment of the present invention while FIG. <b>2</b>(<i>b</i>) is a cross-sectional view showing a light emitting diode package structure taken along a line A-A′ of FIG. <b>2</b>(<i>a</i>). Referring to FIG. <b>2</b>(<i>a</i>), the transparent insulating carrier base <b>30</b> is formed with a recess <b>31</b> in an approximately central region thereof. The recess <b>31</b> has a bottom surface <b>32</b> and two sidewall surfaces <b>33</b><i>a </i>and <b>33</b><i>b</i>. For example, the transparent insulating carrier base <b>30</b> is made of glass. Two planar metal layers <b>34</b><i>a </i>and <b>34</b><i>b</i>, which are separated from each other, are formed in a region other than the recess <b>31</b> on the top surface of the transparent insulating carrier base <b>30</b>. In addition, two metal pads <b>35</b><i>a </i>and <b>35</b><i>b </i>are formed on the planar metal layers <b>34</b><i>a </i>and <b>34</b><i>b </i>to locate in peripheral regions of the transparent insulating carrier base <b>30</b>.

Referring to FIG. <b>2</b>(<i>b</i>), the light emitting diode <b>10</b> is delivered into the recess <b>31</b> such the recess <b>31</b>. For example, the substrate <b>11</b> of the light emitting diode <b>10</b> is fixed onto the bottom surface <b>32</b> by using a transparent adhesive, thereby facilitating the processes followed up. It should be noted that, in the present invention, the light emitting diode <b>10</b> is not limited to the specific material type and constituting structure shown in the drawings and may be of any suitable material types and constituting structures. For example, the material type of the light emitting diode <b>10</b> may be an AlGaInP-based type, an AlGaInN-based type, an InGaN-based type, an AlG as-based type, a SiC-based type, or the like. The light emitting diode <b>10</b> may have such a configuration that the two electrodes are arranged on the same side and the substrate is transparent. Moreover, the light emitting diode <b>10</b> may be designed to emit light through its front side or rear side. The light emitting diode <b>10</b> may further include a reflective layer and a transparent conductive layer.

The recess <b>31</b> according to the present invention has a depth enough for completely accommodating the light emitting diode <b>10</b> within the recess <b>31</b> and preventing the light emitting diode <b>10</b> from appearing beyond the opening of the recess <b>31</b>. Besides, the recess <b>31</b> may have a depth smaller than 10 mm, for example. A wiring <b>36</b><i>a </i>connects the first electrode <b>14</b> and the planar metal layer <b>34</b><i>a </i>while a wiring <b>36</b><i>b </i>connects the second electrode and the planar metal layer <b>34</b><i>b</i>. A resin <b>37</b> fills the recess <b>31</b> and covers the portions of the wirings <b>36</b><i>a </i>and <b>36</b><i>b </i>appearing beyond the recess <b>31</b> in order to seal all of the light emitting diode <b>10</b> and the wirings <b>36</b><i>a </i>and <b>36</b><i>b </i>within the resin <b>37</b>. For example, the resin <b>37</b> may be made of epoxy resin. A material with a high thermal conductivity may be added into the resin <b>37</b> for enhancing the heat dissipating ability of the package structure. Also, a material with a high reflectivity may be added into the resin <b>37</b> for causing part of the light generated from the light emitting diode <b>10</b> toward the resin <b>37</b> to be reflected, thereby enhancing the lighting efficiency. In addition, in order to further enhance the lighting efficiency, a reflective layer (not shown) may be coated on the resin <b>37</b> for causing the light generated from the light emitting diode <b>10</b> to be reflected toward the bottom surface <b>32</b>.

When a power supply is applied to the light emitting diode <b>10</b> through the protruding metal pads <b>35</b><i>a </i>and <b>35</b><i>b</i>, the light emitting diode <b>10</b> radiates light to external space through the substrate <b>11</b> and the transparent insulating carrier base <b>30</b>, as indicated by an arrow of FIG. <b>2</b>(<i>b</i>). As compared with the conventional package structure of FIG. 1, the package structure according to the present invention packages a light emitting diode in a relatively simple process without requiring the precise alignments, thereby increasing the production yield and decreasing the production cost.

FIG. <b>3</b>(<i>a</i>) is a top plan view showing a transparent insulating carrier base <b>40</b> according to a second embodiment of the present invention while FIG. <b>3</b>(<i>b</i>) is a cross-sectional view showing the light emitting diode package structure taken along a line B-B′ of FIG. <b>3</b>(<i>a</i>). Hereinafter only described are differences of the second embodiment from the first embodiment.

Referring to FIGS. <b>3</b>(<i>a</i>) and <b>3</b>(<i>b</i>), the second embodiment according to the present invention is different from the first embodiment according to the present invention in that a recess <b>41</b> of the second embodiment is formed with two stepwise portions. More specifically, a lower sidewall surface <b>43</b><i>a</i>, an intermediate mesa plane <b>44</b><i>a</i>, and an upper sidewall surface <b>45</b><i>a </i>make up one stepwise portion while a lower sidewall surface <b>43</b><i>b</i>, an intermediate mesa plane <b>44</b><i>b</i>, and an upper sidewall surface <b>45</b><i>b </i>make up another stepwise portion. Moreover, a planar metal layer <b>46</b><i>a </i>is formed on both of the intermediate mesa plane <b>44</b><i>a </i>and the upper sidewall surface <b>45</b><i>a </i>while a planar metal layer <b>46</b><i>b </i>is formed on both of the intermediate mesa plane <b>44</b><i>b </i>and the upper sidewall surface <b>45</b><i>b</i>. On the top surface of the transparent insulating carrier base <b>40</b>, in a region other than the recess <b>41</b>, two metal pads <b>47</b><i>a </i>and <b>47</b><i>b </i>are formed separately from each other. The metal pad <b>47</b><i>a </i>is connected with the planar metal layer <b>46</b><i>a </i>while the metal pad <b>47</b><i>b </i>is connected with the planar metal layer <b>46</b><i>b. </i>

The light emitting diode <b>10</b> is delivered into the recess <b>41</b> such that the substrate <b>11</b> of the light emitting diode <b>10</b> is supported by the bottom surface <b>42</b> of the recess <b>41</b>. A wiring <b>48</b><i>a </i>connects the first electrode <b>14</b> and a portion of the planar metal layer <b>46</b><i>a </i>located on the intermediate mesa plane <b>44</b><i>a </i>while a wiring <b>48</b><i>b </i>connects the second electrode <b>15</b> and a portion of the planar metal layer <b>46</b><i>b </i>located on the intermediate mesa plane <b>44</b><i>b</i>. With such a design of the recess <b>41</b> having two stepwise portions, the wirings <b>48</b><i>a </i>and <b>48</b><i>b </i>are completely accommodated within the recess <b>41</b>. Finally, a resin <b>49</b> fills the recess <b>41</b> to seal all of the light emitting diode <b>10</b> and the wirings <b>48</b><i>a </i>and <b>48</b><i>b</i>. For example, the resin <b>49</b> may be made of epoxy resin. A material with a high thermal conductivity may be added into the resin <b>49</b> for enhancing the heat dissipating ability of the package structure. Also, a material with a high reflectivity may be added into the resin <b>49</b> for causing part of the light generated from the light emitting diode <b>10</b> toward the resin <b>49</b> to be reflected, thereby enhancing the lighting efficiency. In addition, in order to further enhance the lighting efficiency, a reflective layer (not shown) may be coated on the resin <b>49</b> for causing the light generated from the light emitting diode <b>10</b> to be reflected toward the bottom surface <b>42</b>.

From comparing FIGS. <b>2</b>(<i>b</i>) and <b>3</b>(<i>b</i>), it is appreciated that the light emitting diode package structure of the second embodiment is of a smaller size than that of the first embodiment because the wirings <b>48</b><i>a </i>and <b>48</b><i>b </i>are completely accommodated within the recess <b>41</b>.

FIG. 4 is a cross-sectional view showing a light emitting diode package structure according to a third embodiment of the present invention. Hereinafter only described are differences of the third embodiment from the first embodiment.

Referring to FIG. 4, the third embodiment according to the present invention is different from the first embodiment according to the present invention in that an insulating carrier base <b>50</b> of the third embodiment is not necessarily transparent and a through hole <b>51</b> instead of a recess is formed in an approximately central region of the insulating carrier base <b>50</b>. The through hole <b>51</b> penetrates the insulating carrier base <b>50</b> to form a lower opening <b>52</b><i>a </i>and an upper opening <b>52</b><i>b</i>. It should be noted that the present invention is not limited to the configuration shown in FIG. <b>4</b> and the aperture of the lower opening <b>52</b><i>a </i>may be larger than, equal to, or smaller than that of the upper opening <b>52</b><i>b. </i>

Under a condition that the lower opening <b>52</b><i>a </i>is temporarily sealed, a transparent resin <b>53</b><i>a </i>is injected through the upper opening <b>52</b><i>b </i>into the through hole <b>51</b> to partially fill the through hole <b>51</b>. Subsequently, the light emitting diode <b>10</b> is delivered into the through hole <b>51</b> from the upper opening <b>52</b><i>b </i>such that the substrate <b>11</b> of the light emitting diode <b>10</b> is supported by the transparent resin <b>53</b><i>a</i>. After the transparent resin <b>53</b><i>a </i>is cured by a baking process, the light emitting diode <b>10</b> is fixed on the transparent resin <b>53</b><i>a </i>in the through hole <b>51</b>. Finally, a wiring connection process is performed and then a transparent resin <b>53</b><i>b </i>fills the through hole <b>51</b> and covers the portions of the wirings <b>36</b><i>a </i>and <b>36</b><i>b </i>appearing beyond the through hole <b>51</b> to seal all of the light emitting diode <b>10</b> and the wirings <b>36</b><i>a </i>and <b>36</b><i>b. </i>

When a power supply is applied to the light emitting diode <b>10</b> through the protruding metal pads <b>35</b><i>a </i>and <b>35</b><i>b</i>, the light emitting diode <b>10</b> radiates light to external space through the substrate <b>11</b> and the transparent resin <b>53</b><i>a</i>, as indicated by an arrow of FIG. <b>4</b>. Since it is not necessary for the light to transmit through the insulating carrier base <b>50</b> to external space, the insulating carrier base <b>50</b> of the third embodiment is not limited to being made of a transparent material such as glass; it may be made of ceramic, AlN, SiC, plastic, resin, a printed circuit board, or a combination thereof. In addition, the insulating carrier base <b>50</b> may be a combination of a plurality of elements, such as a metal core body coated with an insulating material outer film.

FIG. 5 is a cross-sectional view showing a light emitting diode package structure according to a fourth embodiment of the present invention. Hereinafter only described are differences of the fourth embodiment from the second embodiment.

Referring to FIG. 5, the fourth embodiment according to the present invention is different from the second embodiment according to the present invention in that an insulating carrier base <b>60</b> of the fourth embodiment is not necessarily transparent and a through hole <b>61</b> instead of a recess is formed in an approximately central region of the insulating carrier base <b>60</b>. The through hole <b>61</b> penetrates the insulating carrier base <b>60</b> to form a lower opening <b>62</b><i>a </i>and an upper opening <b>62</b><i>b</i>. It should be noted that the present invention is not limited to the configuration shown in FIG. <b>5</b> and the aperture of the lower opening <b>62</b><i>a </i>may be larger than, equal to, or smaller than that of the upper opening <b>62</b><i>b. </i>

Like the recess <b>41</b> of the second embodiment, the through hole <b>61</b> is formed with two stepwise portions. With a manufacturing method similar to that in the third embodiment, the substrate <b>11</b> of the light emitting diode <b>10</b> is supported by the transparent resin <b>63</b><i>a </i>and then a transparent resin <b>63</b><i>b </i>fills the through hole <b>61</b> and covers the wirings <b>48</b><i>a </i>and <b>48</b><i>b </i>to seal all of the light emitting diode <b>10</b> and the wirings <b>48</b><i>a </i>and <b>48</b><i>b</i>. The insulating carrier base <b>60</b> is not limited to being made of a transparent material such as glass; it may be made of ceramic, AlN, SiC, plastic, resin, a printed circuit board, or a combination thereof. In addition, the insulating carrier base <b>60</b> may be a combination of a plurality of elements, such as a metal core body coated with an insulating material outer film.

From comparing FIGS. 4 and 5, it is appreciated that the light emitting diode package structure of the fourth embodiment is of a smaller size than that of the third embodiment because the wirings <b>48</b><i>a </i>and <b>48</b><i>b </i>are completely accommodated within the through hole <b>61</b>.

FIG. 6 is a cross-sectional view showing a light emitting diode package structure according to a fifth embodiment of the present invention. Hereinafter only described are differences of the fifth embodiment from the third embodiment.

In the fifth embodiment, a lower resin portion <b>73</b><i>a </i>and an upper resin portion <b>73</b><i>b </i>are used for sealing all of the light emitting diode <b>10</b> and the wirings <b>36</b><i>a </i>and <b>36</b><i>b</i>. The lower resin portion <b>73</b><i>a </i>is made of a transparent material and serves as a light-transmitting channel. Preferably, the lower resin portion <b>73</b><i>a </i>is made of a material having a refraction index which matches the refraction index of the substrate <b>11</b> in such a manner that the total reflection between the substrate <b>11</b> and the lower resin portion <b>73</b><i>a </i>is reduced. The upper resin portion <b>73</b><i>b </i>may be made of a reflective material or a resin doped with a reflective material and serves to reflect the light toward the lower resin portion <b>73</b><i>a</i>. In addition, in order to further enhance the lighting efficiency, a reflective layer (not shown) may be coated on the upper resin portion <b>73</b><i>b </i>for causing the light generated from the light emitting diode <b>10</b> to be reflected toward the lower opening <b>52</b><i>a</i>. Moreover, an optical lens <b>74</b> may be arranged on the lower opening <b>52</b><i>a </i>of the through hole <b>51</b> for controlling the light radiating out of the light emitting diode package structure.

FIG. 7 is a cross-sectional view showing a light emitting diode package structure according to a sixth embodiment of the present invention. Hereinafter only described are differences of the sixth embodiment from the fourth embodiment.

In the sixth embodiment, a lower resin portion <b>83</b><i>a </i>and an upper resin portion <b>83</b><i>b </i>are used for sealing all of the light emitting diode <b>10</b> and the wirings <b>48</b><i>a </i>and <b>48</b><i>b</i>. The lower resin portion <b>83</b><i>a </i>is made of a transparent material and serves as a light-transmitting channel. Preferably, the lower resin portion <b>83</b><i>a </i>is made of a material having a refraction index which matches the refraction index of the substrate <b>11</b> in such a manner that the total reflection between the substrate <b>11</b> and the lower resin portion <b>83</b><i>a </i>is reduced. The upper resin portion <b>83</b><i>b </i>may be made of a reflective material or a resin doped with a reflective material and serves to reflect the light toward the lower resin portion <b>83</b><i>a</i>. In addition, the lower resin portion <b>83</b><i>a </i>may be doped with a fluorescent material such as phosphor, or a fluorescent layer <b>84</b> may be coated on the lower opening <b>62</b><i>a </i>of the through hole <b>61</b>. Depending on the porosity of the fluorescent material and the thickness of the fluorescent layer <b>84</b>, the wavelength of the light radiated out of the light emitting diode package structure can be changed in order to provide a light of a desirable color.

While the invention has been described by way of examples and in terms of preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications. For example, the insulating carrier base, the recess, and the upper and lower openings of the through hole are not limited to a rectangle in a plane view and may be in any available shapes such as a circle, an ellipse, a polygon, etc.